Phosphor composite material and phosphor composite member

ABSTRACT

Disclosed is a phosphor composite material which can be fired at low temperatures and enables to obtain a phosphor composite member which is excellent in weather resistance and reduced in deterioration after long use. Also disclosed is a phosphor composite member obtained by firing such a phosphor composite material. Specifically disclosed is a phosphor composite material composed of a glass powder and a phosphor powder, which is characterized in that the glass powder is composed of SnO—P 2 O 5 —B 2 O 3  glass.

TECHNICAL FIELD

The present invention relates to a phosphor composite material and aphosphor composite member used in a device such as an LED or an LD.

BACKGROUND ART

In recent years, white LEDs have been expected to be applied toillumination as the next-generation light sources instead ofincandescent lamps or fluorescent lamps.

In an LED element for attaining wavelength-conversion by use of aphosphor, the light-emitting surface of its LED chip is molded with anorganic binder resin containing a phosphor powder. When light raysemitted from the LED chip pass through this molded region, the lightrays are wholly absorbed into the phosphor so that the wavelengthsthereof are converted to different wavelengths, or the light rays arepartially absorbed into the phosphor so that the converted light raysare combined with the transmitted light rays. In this way, desired lightrays are emitted.

However, there remains a problem that the mold resin, which constitutesthe LED element, is deteriorated by high-power light rays, which haveshort wavelengths in the range from blue wavelengths to ultraviolet raywavelengths, so that the resin is discolored.

In order to solve the problem, in Patent Document 1, proposed is aphosphor composite member about which a material containing a lead-freeglass powder having a softening point of 500° C. or higher and aphosphor powder is fired at a temperature not lower than the softeningpoint of the glass to disperse the phosphor powder in the glass.

With the phosphor composite member disclosed in Patent Document 1, thephosphor powder is dispersed in the glass, which is an inorganicmaterial; thus, it is possible to obtain a product which is chemicallystable so as to be less deteriorated, and which is less discolored bylight rays emitted therefrom.

Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No.2003-258308

Patent Document 2: JP-A No. 2005-11933

DISCLOSURE OF THE INVENTION

However, some commercially available phosphors are low in heatresistance. There is caused a problem that when such a phosphor issintered together with a lead-free glass powder having a softening pointof 500° C. or higher, the phosphor is deteriorated by heat in thesintering, so as to give a low light-emitting efficiency.

In order to solve the problem, it is considered that the phosphor isdispersed in a low melting point glass as disclosed in Patent Document2. In general, however, as glass has a lower melting point, the glassreacts with the phosphor upon sintering, and the sintered product isdiscolored so that the transmittance of the sintered product becomeslower, and thus there is caused a problem that the light-emittingefficiency is largely lowered. Moreover, the weather resistance of theglass is low so that the surface thereof degenerates in use in anenvironment being large in humidity. As a result, there arises a problemthat the transmittance of the sintered product falls so that thelight-emitting efficiency is largely lowered.

An object of the present invention is to provide a phosphor compositematerial which can be fired at low temperature and does not react easilywith a phosphor, and which further enables to obtain a phosphorcomposite member that is excellent in weather resistance and reduced indeterioration after long use; and a phosphor composite member obtainedby firing the same.

The phosphor composite material of the present invention is a phosphorcomposite material comprising a glass powder and a phosphor powder,wherein the glass powder is composed of SnO—P₂O₅—B₂O₃ glass.

Moreover, the phosphor composite member of the present invention is amember obtained by firing the phosphor composite material.

EFFECT OF THE INVENTION

The phosphor composite material of the present invention comprises aglass powder which has a low softening point, does not react easily witha phosphor, and is excellent in weather resistance as well as a phosphorpowder. Therefore, the phosphor composite member obtained by firing thephosphor composite material of the present invention can be a phosphorcomposite member which can be fired at low temperature, does not reacteasily with the phosphor, and is excellent in weather resistance andreduced in deterioration after long use.

BEST MODE FOR CARRYING OUT THE INVENTION

The glass powder in the phosphor composite material of the presentinvention has a basic composition wherein B₂O₃ is incorporated intoSnO—P₂O₅ glass which is a low melting point glass. In general, SnO—P₂O₅glass which is a low melting point glass is low in weather resistance,and reacts with a phosphor when it is mixed with the phosphor and firedto result in the light-emitting efficiency being lowered. However, inthe glass in the present invention, B₂O₃ is contained which is acomponent for preventing reaction with the phosphor and improvingweather resistance. For this reason, even the phosphor compositematerial comprising the low melting point glass powder can give aphosphor composite member wherein reaction with the phosphor is lesscaused and an excellent weather resistance is exhibited.

It is preferred to contain B₂O₃ in an amount of 1% or more by mole inorder to prevent reaction with the phosphor and improve the weatherresistance. However, if the content of B₂O₃ is large, the softeningpoint of the glass tends to rise so that the phosphor composite materialis not easily fired at low temperature. Conversely, the content ispreferably set to 30% or less by mole, otherwise the glass thus reactswith the phosphor and the weather resistance falls easily. The range ofthe B₂O₃ content is preferably from 2 to 20%, more preferably from 4 to20%, most preferably from 4 to 18%.

With the glass powder in the invention, the value by mole of SnO/P₂O₅ ispreferably set into the range of 0.9 to 16. If the value of SnO/P₂O₅ issmaller than 0.9, the softening point of the glass tends to rise so thatthe phosphor composite material is not easily fired at low temperatureand the phosphor is easily deteriorated. Additionally, the weatherresistance tends to fall remarkably. On the other hand, if the value ofSnO/P₂O₅ is larger than 16, devitrification grains derived from Snprecipitate in the glass so that the transmittance of the glass tends tofall. As a result, a phosphor composite member having a highlight-emitting efficiency is not easily obtained. The range of the valueof SnO/P₂O₅ is preferably from 1.5 to 16, more preferably from 1.5 to10, most preferably from 2 to 5.

The glass powder in the present invention is preferably made of a glasshaving an internal transmittance of 80% or more at a thickness of 1 mmand a wavelength of 588 nm. When the internal transmittance of the glassis set to 80% or more, the transmittance of excited light and that ofconverted light generated by the excited light become so high that thelight-emitting efficiency of the phosphor composite member can beimproved. If the internal transmittance of the glass is lower than 80%,a phosphor composite member having a high light-emitting efficiency isnot easily obtained. The range of the internal transmittance of theglass is more preferably 92% or more, more preferably 93% or more.

A glass having a high internal transmittance can be obtained by usingand melting glass ingredients in which an amount of colored impuritiessuch as iron, chromium, cobalt, copper and nickel is small in order torestrain a fall in the transmittance due to light absorption, andmelting the glass under a reduction atmosphere (non-oxidizing atmospheresuch as N₂ gas or Ar gas) or adding a small amount of a reducing agentsuch as metallic aluminum to glass ingredients and melting the glassingredients in order to restrain a fall in the internal transmittancedue to the precipitation of devitrification grains derived from Sn.

Furthermore, it is preferred that the glass powder in the presentinvention has a softening point of 400° C. or lower. If the softeningpoint is set to 400° C. or lower, a phosphor composite member where thephosphor is less deteriorated can be obtained even when a phosphor lowin heat resistance is used. If the softening point is higher than 400°C., the phosphor tends to be deteriorated and the light-emittingefficiency of the phosphor composite member lowers easily when thephosphor low in heat resistance is used. The range of the softeningpoint is more preferably 380° C. or lower.

The SnO—P₂O₅—B₂O₃ glass powder of the present invention is notparticularly limited as far as the glass is a glass which has a highinternal transmittance and a low softening point, does not react easilywith the phosphor, and is excellent in weather resistance. It isparticularly preferred to use a glass, in a mole percentage, having thefollowing composition: 35 to 80% of SnO, 5 to 40% of P₂O₅, 1 to 30% ofB₂O₃, 0 to 10% of Al₂O₃, 0 to 10% of SiO₂, 0 to 10% of Li₂O, 0 to 10% ofNa₂O, 0 to 10% of K₂O, 0 to 10% of Li₂O+Na₂O+K₂O, 0 to 10% of MgO, 0 to10% of CaO, 0 to 10% of SrO, 0 to 10% of BaO and 0 to 10% ofMgO+CaO+SrO+BaO, and satisfying the following: the ratio by mole ofSnO/P₂O₅ is from 0.9 to 16.

The reason why the glass composition is limited as described above inthe present invention is as follows.

SnO is a component for forming the skeleton of the glass and furtherlowering the softening point. The content thereof is from 35 to 80%. Ifthe content of SnO is low, the softening point of the glass tends torise, the phosphor composite material is not easily fired at lowtemperature, and the phosphor is easily deteriorated. On the other hand,if the content is high, devitrification grains derived from Snprecipitate in the glass so that the transmittance of the glass tends tofall. As a result, a phosphor composite member having a highlight-emitting efficiency is not easily obtained. Additionally, thematerial does not easily vitrify. The range of the content of SnO ismore preferably from 40 to 70%, even more preferably from 50 to 70%,most preferably from 55 to 65%.

P₂O₅ is a component for forming the skeleton of the glass. The contentthereof is from 5 to 40%. If the content of P₂O₅ is low, the materialdoes not easily vitrify. On the other hand, if the content is high, thesoftening point of the glass tends to rise, the phosphor compositematerial is not easily fired at low temperature, and the phosphor iseasily deteriorated. Additionally, the weather resistance tends to fallremarkably. The range of the content of P₂O₅ is more preferably from 10to 30%, even more preferably from 15 to 24%.

In order to lower the softening point and further stabilize the glass,the value of SnO/P₂O₅ is preferably set in the range of 0.9 to 16 in amole ratio. If the value of SnO/P₂O₅ is lower than 0.9, the softeningpoint of the glass tends to rise, the phosphor composite material is noteasily fired at low temperature, and the phosphor is easilydeteriorated. Additionally, the weather resistance tends to fallremarkably. On the other hand, if the value of SnO/P₂O₅ is higher than16, devitrification grains derived from Sn precipitate in the glass sothat the transmittance of the glass tends to fall. As a result, aphosphor composite member having a high light-emitting efficiency is noteasily obtained. The range of the value of SnO/P₂O₅ is more preferablyfrom 1.5 to 16, even more preferably from 1.5 to 10, most preferablyfrom 2 to 5.

B₂O₃ is a component for preventing reaction with the phosphor andimproving the weather resistance. B₂O₃ is also a component forstabilizing the glass. The content thereof is from 1 to 30%. If thecontent of B₂O₃ is low, the above-mentioned advantageous effects are noteasily obtained. On the other hand, if the content is high, the glassconversely comes to react easily with the phosphor or be poor in weatherresistance. In addition, the softening point of the glass tends to rise,the phosphor composite material is not easily fired at low temperature,and the phosphor is easily deteriorated. The content of B₂O₃ is morepreferably from 2 to 20%, even more preferably from 4 to 18%.

Al₂O₃ is a component for stabilizing the glass. The content thereof isfrom 0 to 10%. If the content of Al₂O₃ is high, the softening point ofthe glass tends to rise, the phosphor composite material is not easilyfired at low temperature, and the phosphor is easily deteriorated. Thecontent of Al₂O₃ is more preferably from 0 to 7%, even more preferablyfrom 1 to 5%.

SiO₂ is a component for stabilizing the glass similar to Al₂O₃. Thecontent thereof is from 0 to 10%. If the content of SiO₂ is high, thesoftening point of the glass tends to rise, the phosphor compositematerial is not easily fired at low temperature, and the phosphor iseasily deteriorated. Additionally, the glass easily undergoes phaseseparation. The content of SiO₂ is more preferably from 0 to 7%, evenmore preferably from 0 to 5%.

Li₂O is a component for making the softening point of the glassremarkably low, and improving the light-emitting efficiency of thephosphor when the phosphor composite member is formed. The contentthereof is from 0 to 10%. If the content of Li₂O is high, the glasseasily becomes remarkably unstable, and the material does not easilyvitrify. The content of Li₂O is more preferably from 0 to 7%, even morepreferably from 1 to 5%.

Na₂O is a component for lowering the softening point of the glass, andimproving the light-emitting efficiency of the phosphor somewhat whenthe phosphor composite member is formed. The content thereof is from 0to 10%. If the content of Na₂O is high, the glass easily becomesunstable and the glass ingredients do not easily vitrify. The content ofNa₂O is more preferably from 0 to 7%, even more preferably from 0 to 5%.

K₂O is a component for lowering the softening point of the glasssomewhat, and improving the light-emitting efficiency of the phosphorwhen the phosphor composite member is formed. The content thereof isfrom 0 to 10%. If the content of K₂O is high, the glass easily becomesunstable and the glass ingredients do not easily vitrify. The content ofK₂O is more preferably from 0 to 7%, even more preferably from 1 to 5%.

The total content of Li₂O, Na₂O and K₂O is preferably set in the rangeof 0 to 10%. If the content of these components becomes more than 10%,the glass easily becomes unstable and the glass ingredients do noteasily vitrify. The range of the content of Li₂O+Na₂O+K₂O is morepreferably from 0 to 7%, even more preferably from 1 to 5%.

MgO is a component for stabilizing the glass and vitrifying the glassingredients with ease, and improving the light-emitting efficiency ofthe phosphor remarkably when the phosphor composite member is formed.The content thereof is from 0 to 10%. If the content of MgO is high, theglass devitrifies so easily that the transmittance of the glass tends tofall. As a result, a phosphor composite member having a highlight-emitting efficiency is not easily obtained. The content of MgO ismore preferably from 0 to 7%, even more preferably from 1 to 5%.

CaO is a component for stabilizing the glass and vitrifying the glassingredients with ease. The content thereof is from 0 to 10%. If thecontent of CaO is high, the glass devitrifies so easily that thetransmittance of the glass tends to fall. As a result, a phosphorcomposite member having a high light-emitting efficiency is not easilyobtained. The content of CaO is more preferably from 0 to 7%, even morepreferably from 0 to 5%.

SrO is a component for stabilizing the glass and vitrifying the glassingredients with ease. The content thereof is from 0 to 10%. If thecontent of SrO is high, the glass devitrifies so easily that thetransmittance of the glass tends to fall. As a result, a phosphorcomposite member having a high light-emitting efficiency is not easilyobtained. The content of SrO is more preferably from 0 to 7%, even morepreferably from 0 to 5%.

BaO is a component for stabilizing the glass and vitrifying the glassingredients with ease. The content thereof is from 0 to 5%. If thecontent of BaO is high, the glass remarkably devitrifies so easily thatthe transmittance of the glass tends to fall. As a result, a phosphorcomposite member having a high light-emitting efficiency is not easilyobtained. The content of BaO is more preferably from 0 to 3%, even morepreferably from 0 to 1%.

The total content of MgO, CaO, SrO and BaO is preferably set in therange of 0 to 10%. If the content of these components is more than 10%,the glass devitrifies so easily that the transmittance of the glasstends to fall. As a result, a phosphor composite member having a highlight-emitting efficiency is not easily obtained. The range of thecontent of MgO+CaO+SrO+BaO is more preferably from 0 to 7%, even morepreferably from 1 to 5%.

Various components other than the above-mentioned components may beadded as far as the subject matter of the present invention is notdamaged. For example, in order to improve the weather resistance, ZnO,Ta₂O₅, TiO₂, Nb₂O₅, Gd₂O₃, and/or La₂O₃ may be added in a total amountof 10% or less.

However, since color components such as Fe₂O₃, Cr₂O₃, CoO, CuO and NiOcause the glass to be colored so as to lower the internal transmittanceof the glass, it is preferred to control the total content of thesecomponents to 0.02% or less.

The glass powder in the phosphor composite material of the presentinvention can be obtained by selecting glass ingredients where theamount of colored impurities is small such that the content of colorcomponents in the glass is set to 0.02% or less, blending the glassingredients with each other to give a glass composition in theabove-mentioned glass composition range, putting the blended glassingredients into a crucible, melting the ingredients under a reductionatmosphere to yield a glass ingot, pulverizing the ingot, andclassifying the resultant particles.

The phosphor powder in the phosphor composite material of the presentinvention is not particularly limited as far as the powder has aluminescence peak in a visible range. The visible range in the presentinvention refers to a range of 380 to 780 nm. Examples of such aphosphor include oxides, nitrides, oxynitrides, chlorides, oxychlorides,sulfides, oxysulfides, halides, chalcogenides, aluminates,halophosphoric acid chloride, and YAG compounds. Phosphors such asnitrides, oxynitrides, chlorides, oxychlorides, sulfides, oxysulfides,halides, chalcogenides, aluminates, and halophosphoric acid chloride areeach caused to react with the glass by heating upon firing, abnormalreaction such as foaming and discoloration is easily caused, and thedegree thereof becomes more remarkable as the firing temperature ishigher. Even if such a phosphor is used, the phosphor composite materialcan be fired at a low temperature of 400° C. or lower in the presentinvention since the softening point of the glass is low; thus, thephosphor can be used.

The light-emitting efficiency of the phosphor composite member is varieddepending on the kind and the content of the phosphor particlesdispersed in the glass, the thickness of the phosphor composite member,and others. The content of the phosphor and the thickness of thephosphor composite member may be adjusted to achieve an optimallight-emitting efficiency. If the amount of the phosphor is too large,the composite material is not easily sintered or the porosity is madelarge so as to result in problems that, for example, exited light is noteasily radiated effectively to the phosphor and that the mechanicalstrength of the phosphor composite member decreases easily. On the otherhand, if the amount is too small, it is difficult to cause the member toemit light sufficiently.

Therefore, the blend ratio of the glass powder to the phosphor powder(glass powder:the phosphor powder) in the phosphor composite material ispreferably from 99.99:0.01 to 70:30, more preferably form 99.95:0.05 to80:20, particularly preferably from 99.92:0.08 to 85:15.

The phosphor composite member of the present invention can be obtainedby firing the phosphor composite material of the present invention.

The firing atmosphere may be air. When a denser sintered body isobtained or when reaction between the glass and the phosphor isdecreased, the material is preferably fired in a reduced pressure orvacuum atmosphere or in an inert gas atmosphere such as nitrogen orargon.

The firing temperature is preferably from 300 to 400° C. If the firingtemperature is higher than 400° C., the phosphor is deteriorated or theglass reacts with the phosphor so that the light-emitting efficiency mayremarkably fall. If the firing temperature is lower than 300° C., theporosity of the sintered body increases so that the light transmittancemay fall.

The form of the phosphor composite material of the present inventionwhen the phosphor composite material is fired to yield a phosphorcomposite member is not particularly limited, and may be, for example, amolded body obtained by press-molding the powder of the phosphorcomposite material into a desired shape, a paste form, or a green-sheetform.

When the powder of the phosphor composite material of the presentinvention is press-molded to prepare a phosphor composite member, thephosphor composite member can be obtained by adding, to the phosphorcomposite material comprising glass powders and phosphor powders, aresin binder in an amount of 0 to 5% by mass, press-molding the mixturein a mold to produce a preliminary molded body, subjecting thepreliminary molded body to binder-removing treatment at a temperature of250° C. or lower, and then firing the resultant at about 300 to 400° C.

The used resin binder is desirably a resin binder where thedecomposition-ended temperature of the resin is 250° C. or lower.Examples thereof include nitrocellulose, polyisobutyl acrylate, andpolyethyl carbonate. These may be used alone or in a mixture form.

When the phosphor composite material of the present invention is used ina paste form, it is preferred to use a binder, a solvent and the likewith the phosphor composite material comprising glass powders andphosphor powders, and make the components into a paste. The ratio of thephosphor composite material in the whole of the paste is generally from30 to 90% by mass.

The binder is a component for heightening the film strength afterdrying, or giving softness thereto. The content thereof is generallyfrom about 0.1 to 20% by mass. Examples of the binder include polybutylmethacrylate, polyvinyl butyral, polymethyl methacrylate, polyethylmethacrylate, ethylcellulose, and nitrocellulose. These may be usedalone or in a mixture form.

The solvent is used for making the material into a paste form. Thecontent thereof is generally from about 10 to 50% by mass. Examples ofthe solvent include terpineol, isoamyl acetate, toluene, methyl ethylketone, diethylene glycol monobutyl ether acetate, and2,2,4-trimethyl-1,3 pentadiol monoisobutyrate. These may be used aloneor in a mixture form.

The paste can be produced by preparing the phosphor composite material,the binder, the solvent and on the like, and kneading these componentsat a predetermined ratio.

In order to form a phosphor composite member by use of such a paste, asubstrate made of an inorganic material having a thermal expansioncoefficient similar to that of the phosphor composite member isprepared, and the paste is applied onto the substrate by screenprinting, batch coating or the like to form the applied layer having apredetermined film thickness. Thereafter, the resultant is dried andfired at about 300 to 400° C., and then the inorganic material substrateis taken off. In this way, a predetermined phosphor composite member canbe formed.

When the phosphor composite material of the present invention is used ina green-sheet form, a binder, a plasticizer, a solvent and on the likeare used with the phosphor composite material comprising glass powdersand phosphor powders, and the components are made into a green sheet.

The ratio of the phosphor composite material in the green sheet isgenerally from about 50 to about 80% by mass. The binder and the solventthat can be used may be the same as used in the preparation of theabove-mentioned paste. The blend percentage of the binder is generallyfrom about 0.1 to about 30% by mass, and the blend percentage of thesolvent is generally from about 1 to about 40% by mass.

The plasticizer is a component for controlling the dry speed and givingsoftness to the dried film. The content thereof is generally from about0 to about 10% by mass. Examples of the plasticizer include dibutylphthalate, butylbenzyl phthalate, dioctyl phthalate, diisooctylphthalate, dicapryl phthalate, and dibutyl phthalate. These may be usedalone or in a mixture form.

In an ordinary method for forming the green sheet, the above-mentionedphosphor composite material, binder and plasticizer, and the like areprepared, and then the solvent is added thereto so as to prepare aslurry. The slurry is made into a sheet form on a film made ofpolyethylene terephthalate (PET) or the like by a doctor blade method.After the formation into the sheet, the sheet is dried to remove theorganic solvent and the like and to produce the green sheet.

In order to form a phosphor composite member using the thus obtainedgreen sheet, a substrate made of an inorganic material having a thermalexpansion coefficient similar to that of the phosphor composite memberis prepared, the green sheet is laminated on the substrate, and then theresultant is thermally compressed to form an applied layer. Thereafter,the resultant is fired as in the case of the paste, and then theinorganic material substrate is taken off to obtain a phosphor compositemember.

When the thus obtained phosphor composite member is arranged on alight-emitting side surface of a light-emitting chip of an LED, lightrays emitted from the light-emitting chip can be converted to light rayshaving different wavelengths.

The phosphor composite member of the present invention is, for example,a member for converting light rays having wavelengths of 300 to 500 nmto visible rays. The conversion property thereof can be variouslyadjusted depending on the kind of the phosphor to be used.

EXAMPLES

The present invention will be described by way of the followingexamples.

Tables 1 to 4 show Examples (samples Nos. 1 to 24) of the invention, andComparative Examples (Samples Nos. 25 and 26).

TABLE 1 Glass Composition (% by mole) 1 2 3 4 5 6 7 SnO 62.0 62.0 62.062.0 62.0 62.0 62.0 P₂O₅ 21.0 21.0 21.0 21.0 21.0 21.0 21.0 B₂O₃ 11.511.5 11.5 11.5 11.5 11.5 11.5 Al₂O₃ 2.5 2.5 2.5 2.5 2.5 2.5 2.5 SiO₂ 3.0— — — — — — Li₂O — 3.0 — — — — — Na₂O — — 3.0 — — — — K₂O — — — 3.0 — —— MgO — — — — 3.0 — — CaO — — — — — 3.0 — SrO — — — — — — 3.0 BaO — — —— — — — ZnO — — — — — — — NiO — — — — — — — SnO/P₂O₅ 2.9 2.9 2.9 2.9 2.92.9 2.9 Softening Point (° C.) 350 335 340 340 350 350 350 FiringTemperature (° C.) 350 340 345 345 350 355 355 Internal Transmittance(%) 95 97 96 98 98 95 97 Reaction Between ◯ ◯ ◯ ◯ ◯ ◯ ◯ Glass andPhosphor Light-Emitting Efficiency (lm/W) 19 20 19 20 19 21 19 <BeforeWeather Resistance Test> Light-Emitting Efficiency (lm/W) 19 20 19 20 1921 19 <After Weather Resistance Test> Surface State ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ <AfterWeather Resistance Test>

TABLE 2 Glass Composition (% by mole) 8 9 10 11 12 13 14 SnO 62.0 62.069.5 66.0 66.0 42.0 71.0 P₂O₅ 21.0 21.0 24.0 22.5 22.5 40.0 5.0 B₂O₃11.5 14.5 1.0 3.0 4.0 13.0 20.0 Al₂O₃ 2.5 2.5 3.0 5.0 4.0 3.0 — SiO₂ — —2.5 1.0 2.0 — — Li₂O — — — — — — — Na₂O — — — 2.5 1.5 — — K₂O — — — — —— — MgO — — — — — — 1.0 CaO — — — — — — 3.0 SrO — — — — — — — BaO 3.0 —— — — 2.0 — ZnO — — — — — — — NiO — — — — — — — SnO/P₂O₅ 2.9 2.9 2.9 2.92.9 1.1 14.0 Softening Point (° C.) 360 345 330 320 325 400 330 FiringTemperature (° C.) 365 345 330 330 330 400 330 Internal Transmittance(%) 96 97 98 96 98 97 87 Reaction Between ◯ ◯ ◯ ◯ ◯ ◯ ◯ Glass andPhosphor Light-Emitting Efficiency (lm/W) 18 19 7 12 15 13 14 <BeforeWeather Resistance Test> Light-Emitting Efficiency (lm/W) 18 19 4 10 158 14 <After Weather Resistance Test> Surface State ⊚ ⊚ ◯ ◯ ⊚ ◯ ⊚ <AfterWeather Resistance Test>

TABLE 3 Glass Composition (% by mole) 15 16 17 18 19 20 21 SnO 55.0 64.048.0 36.0 50.0 34.0 62.0 P₂O₅ 15.0 4.0 24.0 18.0 11.0 41.0 21.0 B₂O₃19.0 29.0 22.0 20.0 19.0 17.0 11.5 Al₂O₃ 2.0 2.5 3.0 5.0 5.0 3.0 2.5SiO₂ 3.0 — 6.0 6.0 — — Li₂O 1.5 — — 3.0 — — — Na₂O 1.5 — — — — — — K₂O —— — 4.0 1.0 — — MgO — — 3.0 3.0 4.0 3.0 3.0 CaO 3.0 0.5 — 3.0 3.0 2.0 —SrO — — — — — — — BaO — — — — — — — ZnO — — — 2.0 1.0 — — NiO — — — — —— 0.005 SnO/P₂O₅ 3.7 16.0 2.0 2.0 4.5 0.8 2.9 Softening Point (° C.) 365350 360 380 360 410 350 Firing Temperature (° C.) 365 350 360 380 360410 350 Internal Transmittance (%) 98 89 98 98 98 98 94 Reaction Between◯ ◯ ◯ ◯ ◯ ◯ ◯ Glass and Phosphor Light-Emitting Efficiency (lm/W) 18 1518 17 17 10 16 <Before Weather Resistance Test> Light-EmittingEfficiency (lm/W) 18 15 18 17 17 8 16 <After Weather Resistance Test>Surface State ⊚ ⊚ ⊚ ⊚ ⊚ ◯ ⊚ <After Weather Resistance Test>

TABLE 4 Glass Composition (% by mole) 22 23 24 25 26 SnO 62.0 62.0 62.062.0 — P₂O₅ 21.0 21.0 21.0 21.0 — B₂O₃ 11.5 11.5 11.5 — 45.0 Al₂O₃ 2.52.5 2.5 3.0 5.0 SiO₂ — — — — 5.0 Li₂O — — — — 5.0 Na₂O — — — — 5.0 K₂O —— — — — MgO 3.0 3.0 3.0 — — CaO — — — — — SrO — — — — — BaO — — — — —ZnO — — — 14.0 35.0 NiO 0.01 0.02 0.03 — — SnO/P₂O₅ 2.9 2.9 2.9 2.9 —Softening Point (° C.) 350 350 350 340 570 Firing Temperature (° C.) 350350 350 340 570 Internal Transmittance (%) 90 82 73 90 95 ReactionBetween ◯ ◯ ◯ X X Glass and Phosphor Light-Emitting Efficiency (lm/W) 1410 6 3 <0.1 <Before Weather Resistance Test> Light-Emitting Efficiency(lm/W) 14 10 6 1 — <After Weather Resistance Test> Surface State ⊚ ⊚ ⊚ X— <After Weather Resistance Test>

Each sample in the tables was prepared as follows.

First, ingredients were blended with each other to give a glasscomposition in the tables, and mixed into a uniform state. Next, theblended ingredients were put into an aluminum crucible, and then meltedin a N₂ atmosphere at 900° C. for 2 hours (or melted therein at 1200° C.for 2 hours only about No. 26). Thereafter, a part of the glass melt wascast onto a carbon plate so as to be formed into a plate form, and therest was molded into a film form by use of a roller molding device.Subsequently, the resultant film-form glass was crushed by means of acrusher, and then the resultant was passed through a 325-mesh sieve toyield a classified glass powder. The resultant plate-form glass wasannealed, cut and polished, then the internal transmittance of the glasswas measured, and the softening point of the glass powder was measured.These measured results are shown in the table.

Next, to 99% by mass of the resultant glass powder was added 1% by massof SrBaSiO₄:Eu²⁺ powders (a phosphor having a heat resistance of about500° C.), and the powders were mixed with each other to yield a phosphorcomposite material. Next, the resultant phosphor composite material wasput into a mold, and then press-molded to form a preliminary molded bodyhaving a size of 15 mm×15 mm and having a thickness of 5 mm. Thispreliminary molded body was fired at a firing temperature shown in theTable under a reduced pressure of 100 Pa (1 atm.=1.013×10⁵ Pa), and thenprocessed to yield a phosphor composite member having a size of 10 mm×10mm and having a thickness of 1 mm. With the resultant phosphor compositemember, the reaction between the glass and the phosphor, thelight-emitting efficiency, and the weather resistance were evaluated,and the results are shown in the table.

As illustrated in the tables, in each of the samples Nos. 1-19 and Nos.21-23 in Examples, the softening point of the glass was as low as 400°C. or lower, so that the sample was able to be fired at a temperature of400° C. or lower. Moreover, the internal transmittance of the glass wasas high as 82%, and, in the evaluation of the reaction between the glassand the phosphor, the sintered body was not colored, and thelight-emitting efficiency was as high as 7 lm/W or more. Furthermore,the light-emitting efficiency after the weather resistance test was 4lm/W or more, and the decrease ratio of the light-emitting efficiencydue to the weather resistance test (1—(the light-emitting efficiencybefore the test)/(the light-emitting efficiency after the test)) wasalso as low as 43%. In the sintered body surface after the test, nocloudiness was observed with the naked eye, and the sample was excellentin weather resistance. With the sample No. 20, the internaltransmittance of the glass was 98%, but the softening point of the glasswas as high as 410° C.; thus, the light-emitting efficiency thereof waslower than those in other Examples, wherein B₂O₃ was incorporated to thesame degree in order to restrain the reaction with the phosphor. Withthe sample No. 24, regarding the evaluation of the reaction between theglass and the phosphor, the sintered body was not colored so that theglass and the phosphor were not easily caused to react with each other;however, the internal transmittance of the glass was as low as 73%, sothat the light-emitting efficiency was lower than those in otherExamples.

On the contrary, with the sample No. 25 in Comparative Example, theglass and the phosphor were caused to react with each other upon firing,so that the sintered body was colored, and the light-emitting efficiencywas as low as lm/W. The light-emitting efficiency after the weatherresistance test was 1 lm/W, the decrease ratio of the light-emittingefficiency through the weather resistance test was as large as 67%, andfurther the sintered body surface after the test was cloudy according toan observation with the naked eye. According to an observation with amicroscope, fine cracks and elution of the glass components wererecognized, and the weather resistance was low. Moreover, the glasssoftening point of the sample No. 26 was as high as 570° C., so that thefiring temperature also was high, the phosphor was deteriorated in thefiring so that the light-emitting efficiency was remarkably low.

The softening point of the glass powders was measured with a macro typedifferential thermal analyzer, and the value of a fourth inflectionpoint was defined as the softening point.

The internal transmittance of the glasses was obtained by subjecting theglass formed into a plate form to optical polishing processing so as tohave a thickness of 1 mm, measuring the transmittance and reflectivitythereof at a wavelength of 588 nm with a spectrophotometer, and thenobtaining the internal transmittance (the value obtained by adding thereflectivity on both surfaces of the sample to the transmittance).

The reaction between the glass and the phosphor was evaluated byobserving whether or not the sample (phosphor composite member) obtainedby firing the glass and the phosphor was colored. The individual sampleswere observed with the naked eye, a sample having the sample color(yellow) as the color of the phosphor powder is represented by “o”, anda sample colored into a color different from that of the phosphor powderis represented by “x”. The expression that a sample is colored into acolor different from that of the phosphor powder means that the glassand the phosphor are caused to react with each other by heat upon firingand the phosphor is deteriorated.

The light-emitting efficiency was obtained by setting the sample onto ablue LED (wavelength: 465 nm) operated at a current of 20 mA, measuringthe energy distribution spectrum of lights emitted from the uppersurface of the sample in an integrating sphere, multiplying theresultant spectrum by the relative luminosity to calculate the totalluminous flux, and then dividing the resultant total luminous flux bythe electric power (0.072 W) of the light source.

The weather resistance was evaluated by allowing the phosphor compositemember to stand still under conditions 2 atmospheres in pressure, 95% inhumidity and at a temperature of 121° C. in a pressure cooker testmachine for 24 hours, and then observing the light-emitting efficiencyof the sample after the test and whether or not the surface thereofbecame cloudy. The light-emitting efficiency after the test was obtainedas described above. About the presence or absence of cloudiness on theindividual sample surfaces after the test, the sample surfaces wereobserved with the naked eye and a microscope, a sample where cloudinessdue to fine cracks or the elution of the glass components or the likewas not found with the naked eye and the microscope is represented by“⊙”, a sample where cloudiness was not found with the naked eye but wasfound with the microscope is represented by “o”, and a sample wherecloudiness was found with the naked eye and the microscope isrepresented by “x”.

INDUSTRIAL APPLICABILITY

The phosphor composite material and the phosphor composite member of thepresent invention are not limited to use for an LED, and may be used forproducts which emit high-power excited light, such as a laser diode.

1. A phosphor composite material comprising a glass powder and aphosphor powder, wherein the glass powder is a SnO—P₂O₅—B₂O₃ glass. 2.The phosphor composite material according to claim 1, wherein theSnO—P₂O₅—B₂O₃ glass contains B₂O₃ in an amount of 1 to 30% by mole. 3.The phosphor composite material according to claim 1, wherein in theSnO—P₂O₅—B₂O₃ glass, the ratio of SnO/P₂O₅ is from 0.9 to 16 in a moleratio.
 4. The phosphor composite material according to claim 1, whereinthe SnO—P₂O₅—B₂O₃ glass, in a mole percentage, has the followingcomposition: 35 to 80% of SnO, 5 to 40% of P₂O₅, 1 to 30% of B₂O₃, 0 to10% of Al₂O₃, 0 to 10% of SiO₂, 0 to 10% of Li₂O, 0 to 10% of Na₂O, 0 to10% of K₂O, 0 to 10% of Li₂O+Na₂O+K₂O, 0 to 10% of MgO, 0 to 10% of CaO,0 to 10% of SrO, 0 to 10% of BaO and 0 to 10% of MgO+CaO+SrO+BaO, andsatisfies the following: the ratio of SnO/P₂O₅ is from 0.9 to
 16. 5. Thephosphor composite material according to claim 1, wherein theSnO—P₂O₅—B₂O₃ glass has a softening point of 400° C. or lower.
 6. Thephosphor composite material according to claim 1, wherein the blendratio by mass of the glass powder to the phosphor powder (the glasspowder:the phosphor powder) is from 99.99:0.01 to 70:30.
 7. A phosphorcomposite member obtained by firing the phosphor composite materialaccording to claim
 1. 8. The phosphor composite member according toclaim 7, converting light rays having a wavelength of 300 to 500 nm tovisible rays.